Investigators have been unable to identify 1,271 victims of the attacks

The unidentified remains of more than 1,000 victims of the World Trade Center attacks in New York are to be kept at the site's memorial until science can identify them, according to the New York Times newspaper.

More than 12,000 body parts will be interred at the rebuilt site at the request of many of the victims' relatives, the newspaper said.

The remains are to be slowly dried and when free of moisture they will be vacuum-sealed in opaque white pouches.

The procedure will relieve the memorial designers of having to include a refrigeration or freezer system in their plans and will also preserve the remains for future study.

"Our job isn't to inter them and forget about them," said Shiya Ribowsky, an official with the city medical examiner's office.

This is a very respectful and practical way for caring for these remains in perpetuity

Shiya Ribowsky, New York medical examiner's office

"Our job is to inter them and if technology changes in the future, and we have a better chance to identify them, we will have to keep and preserve the remains in such a way that we can use this new technology," Mr Ribowsky said.

Since the 11 September attacks in 2001, the medical examiner's office has recovered 19,936 body parts and has been trying to match them with the 2,792 people listed as missing.

Most of the remains have not been identified because the DNA, the genetic code unique to each individual, was too badly damaged, the newspaper reported.

More than 5,000 entries from around the world have been submitted after the Lower Manhattan Development Corporation announced its memorial design competition.